Electrical connecting device



April 13, 1965 Filed June 12, 1964 L. E. ROBERTS ELECTRICAL CONNECTINGDEVICE 5 Sheets-Sheet l April 13, 1965 E. ROBERTS ELECTRICAL CONNECTINGDEVICE 5 Sheets-Sheet 2 Filed June 12, 1964 April 13, 1965 E. ROBERTS3,178,669

ELECTRICAL CONNECTING DEVICE Filed June 12. 1964 3 Sheets-Sheet 3 UnitedStates Patent ()7 3,17 8,669 ELECTRICAL CONNECTING DEVICE Lincoln E.Roberts, Harrisburg, Pa., assignor to AMP Incorporated, Harrisburg, Pa.Filed June 12, 1964, Ser. No. 374,801 Claims. (Cl. 339--49) Thisapplication is a continuation-in-part of my copending application,Serial No. 183,542, filed March 29, 1962.

This invention relates to multi-contact electrical connectors and tocontact terminals for such connectors. The phrase rnulti-contactconnector is employed herein with reference to the type of disengageableelectrical connecting device comprising a pair of insulating blockswhich are engageable with each other and which have a plurality ofterminal contacts therein. The terminal contacts are secured to the endsof wires so that upon bringing the blocks into engagement with eachother, the wires are electrically connected. Multi-contact connectingdevices of this type are widely used where disengageaible electricalconnections are required among large numbers of conductors.

An object of the invention is to provide an improved hermaphroditic typemulti-contact electrical connector. A further object is to provide animproved hermaphroditic terminal contact for electrical connectors. Astill further object is to provide a multi-contact electrical connectorin which the individual contacts are closely spaced with respect to eachother thereby permitting a high density of electrical connections in theconnector block. A still further object is to provide a multi-contactelectrical con nector in which the force required to engage anddisengage the blocks with each other is relatively low and whichachieves a low resistance electrical contact between the mated terminalcontacts in the insulating blocks. A still further object is to providea durable and foolproof multi-contact electrical connecting device whichis' not easily damaged in the course of ordinary usage and which issubstantially incapable of improper coupling and decoupling.

These and other objects of the invention are achieved in a preferredembodiment in which the terminal contact comprieses a relativelyelongated web having upstanding sidewalls extending from the oppositesides thereof at each end. Means are provided on the web intermediateits ends for crimping the contact onto the end of an electricalconductor extending between one of the pairs of sidewalls. A pair ofarms extend from the other pair of sidewalls beyond the Web andgenerally along the axis of the contact, one of these arms beingrelatively longer than the other and having a cusp-like inter-mediateportion which is directed inwardly towards the axis of the terminalcontact. The end portion of this first arm diverges slightly withrespect to the contact axis and terminates with an outwardly convexcontact surface. The shorter arm has an intermediate inwardly directedsection and a divergent (with respect to the contact axis) contact rampextending from this intermediate portion. An outwardly directed hook isprovided on the end of this shorter arm to facilitate its mounting in aninsulating block. The terminal contact in accordance with the inventionis matable with an identical contacts upon alignment of the two contactsin opposed axial relationship with respect to each other so that as theyare moved towards each other, the outwardly directed contact' surface ofthe long arm of each contact engages the contact ramp of the other armof the other contact.

The insulating blocks in accordance with the invention which contain theterminal contacts have cavities extending therethrough which conform tothe shape of the terminal contacts in a manner such that the contactscan only be 3,178, 669 Patented Apr. '13, 1965 inserted into thecavities in the proper and intended manner and will be securely held inthe cavities after insertion. The cavities have a rectangular crosssection throughout a substantial portion of their lengths which conformsto the cross section of the sidewalls of the web so that the contactsare firmly'held by the Walls of these cavities bearing against thesidewalls of the web and against the web itself. At its forward end,each cavity has a recess defining a forwardly facing shoulder over whichthe hooked end of the shorter arm extends. This hooked end thus preventsrearward movement of the terminal contact with respect to the blockwhile forward movement thereof is prevented by means of a shoulder inthe cavity which engages the leading edge of the web of the contact. Thesalient advantage of the invention is that a complete connector assemblycomprising two insulating blocks each having a plurality of electricalcontacts therein can be achieved with two identical insulating blocksand a number of identical terminal contacts corresponding to thecavities in the blocks. Moreover, this hermaphroditic effect, with itsadvantages of simplicity and standardization, is achieved withoutsacrifice of electrical reliability, mechanical durability, or contactdensity.

In the drawing:

FIGURE 1 is a perspective view of a contact terminal in accordance witha preferred embodiment of the invention;

FIGURE 2 is a perspective view illustrating the progressive stages ofthe forming of the contact terminal of FIGURE 1 by conventionaldie'stamping and forming operations;

FIGURE 3 is a cross sectional view showing a pair of insulating blocksin accordance with the invention in engagement with each other andshowing contact terminals in only some of the cavities in the block;

FIGURES 4, 5 and 6 are sectional views taken along the lines 4-4, 5-5and 6-6 of FIGURE 3;

FIGURE 7 is a perspective view showing a pair of blocks in accordancewith the invention'in face-to-face relationship and illustrating theorientation of the cavities of the blocks;

FIGURE 8 is a perspective view showing an alternative form of a contactterminal in acordance with the invention; and

FIGURE 9 is a fragmentary plan view, on an enlarged scale, showing thehooked end portion of the short arm 20 of the contact terminal of FIGURE8.

Referring first to FIGURE 1, a preferred form of terminal contact 2 inaccordance with the invention com prises an elongated substantially flatweb 4 having a first pair of parallel sidewalls 6 extending fromopposite sides of its forward end and a second pair of sidewalls 8extending from opposite sides of its rearward end. Intermediate the endsof the web there are provided ferruleforming ears 10 and 12 on oppositesides of the web to permit crimping of the contact onto the conductingcore 14 of a wire and the insulation 16 of the wire as shown in FIGURE3. The wire extends between the sidewalls 8 and along the web andmay becrimped to the terminal contact by means of an automatic orsemi-automatic crimping device as is commonly known to the art.

Arms 18, 20 extend from the forward sidewalls 6 and beyond the forwardend of the Web. The arm 18 has a portion 22 which is immediatelyadjacent to the sidewall and constitutes a planar extention thereof andan intermediate cusp-like portion 24, 26 which is directed inwardlytowards the terminal con-tact axis. The end portion 26, of the arm 18 isslightly divergent with respect to the contact axis and terminates in anoutwardly facing contact surface. Advantageously, an outwardly convexdimple or boss 28 may be provided at this contact surface to facilitatesmooth even engagement of the terminal contact with a mating contact.The extreme end portion of the arm 18 is slightly inwardly curved, againto facilitate mating of the contact with an identical contact asdescribed below.

A relatively short arm 20 extends from the opposite one of the sidewalls6, this arm comprising an initial planar extension 30 of the sidewall,an intermediate abruptly inwardly directed section 32, and a contactramp 34 which extends divergently from this intermediate section andwhich faces towards the contact axis. The extreme end portion 36 of thisarm is reversely outwardly bent to form a hook by means of which thecontact is retained in the block cavity. The inclination of the contactramp 34 is not critical, however, for best results its slope should berelatively gentle for reasons explained below. It will be noted that thehooked end 36 of the arm 30 is disposed laterally with respect to thecontact axis of the plane defined by the sidewalls 8, 6 so that if theend of this arm is flexed inwardly it has a tendency to return to itsnormal position.

Contact terminals in accordance with the invention are advantageouslymanufactured from strip metal by means of progressive die stamping andforming methods. FIG- URE 2 shows the various stages of forming thistype of contact in parallel side-by-side form so that the finished stripcan be fed to an automatic or semi-automatic crimping machine whichsimultaneously crimps the leading contact of the strip onto a wire endand severs this leading contact from the side carrier strips. At thetime of crimping the connecting slug 38 is sheared from the contact at alocation adjacent to the forward end of the web. After shearing, avestige 38' of this connecting slug may remain on the end of the web.

Contacts in accordance with the invention can be mated with an identicalcontact by merely axially aligning the two contacts in face-to-facerelationship and moving them relatively towards each other until thecontact surfaces 28 of each contact engage the contact ramp 34 of theother contact. A preferred form of insulating block is shown in FIGURE 7at 40 which can be engaged with an identical block to form a completeelectrical connector assembly. The blocks 40 each have flanges 42 ontheir ends with openings extending therethrough in which are mountedsuitable jack screw means 44 for holding the blocks in engagement witheach other as is commonly known. The cavities 46 in the blocks whichreceive the contacts extend from the rearward sides 48 to the forward ormating faces 50. Each cavity has a substantially rectangular entrancesection 52 extending inwardly from the rearward side 48. Thisrectangular cavity section has opposed sides 54, 56 which arespaced-apart by a distance substantially equal to the spacing betweenthe external surfaces of the sidewalls 6 and 8. The remaining sides 58,59 of the cavity are spaced-apart by a distance substantially equal tothe height of the contact as measured along the side walls 6, 8 so thatupon insertion, the sidewalls and the web bear against the surfaces ofthe cavity as shown in FIGURE 4. The side 56 of the cavity has a groove60 extending partially inwardly of the rectangular section andterminating in an inwardly inclined surface 62 for reception of thehooked end 36 of the arm 20. The forward end of the rectangular sectionhas ledges 64 on the surface 58 which define rearwardly facing shoulders66 adapted to act as stops for the frontal edge of the contact web.

The cavity cross section is constricted at a location 67 close to themating face 50 and the reduced cross section of the cavity extends toand opens into this mating face. A recess 70 extends inwardly from themating face on the side of the cavity which is adapted to receive theshorter arm 20 of the contact and a curved shoulder 72 is provided atthe end of this recess to function as a bearing surface for the curvedend of the arm. The cross section of the cavity in the constricted area68 is such that the arm 20 is resiliently stressed and has a tendency tospring outwardly when its end is hooked over this shoulder.

Insertion of the contacts into the cavities of the blocks 40 isaccomplished by merely aligning each contact with its respective cavityas shown in FIGURE 3 with the arm 20 in alignment with the groove 60 andmoving the contacts axially through the cavity. Improper insertion isvirtually impossible for the reason that the end 36 of the arm 20 willnot enter the cavity unless this arm is in alignment with the groove.The contacts are moved inwardly of the cavities until the arms snap overthe shoulders as described above and the forward end of the web movesagainst the stops 66. After insertion, the longer arm 18 will projectbeyond the mating face of the cavity by a distance sufiicient to permitits being brought into engagement with the contact ramp of a terminalcontact in a mating connector.

It will be apparent from FIGURE 3 that the force exerted by the long armof each contact on the contact ramp of its mating counterpart is in adirection such that it tends to move the blocks 49 laterally withrespect to each other. Thus, referring to the contacts shown at theright in FIGURE 3, the long arm 18 of the lower contact exerts a forceon the contact ramp of the upper contact which has a component tendingto move the upper block 40 to the right in the drawing. The long arm 18of the upper contact on the other hand exerts a force on the contactramp of the lower contact which would tend to move the lower block 40 tothe left in this Figure. These same force components would be present inall of the contacts in the row of cavities shown in FIGURE 7. It followsthat when the blocks are engaged with each other, these lateral forcecomponets must be overcome as the mating faces 50 of the block movetowards each other. In order to reduce these lateral force components toa minimum and thereby reduce the force required to move the blockstogether to a minimum, it is desirable to orient about half of thecavities in the block in a first attitude and the other half of thecavities in an opposite attitude. Referring to FIGURE 7, the severalrows of cavities extending along the long dimension of the block areidentified by the leters A, B, C, D and E. The cavities in the rows B, Cand D are oriented such that the recesses 70 thereof are on the right inthis figure while the cavities in the end rows A and E are oriented suchthat the recesses 70 are on the left. By virtue of this arrangement, thelateral force components of the contacts'in the blocks are at leastpartially balanced out when the blocks are brought into enagagement witheach other. In the particular embodiment shown, three of the rows areoriented with the cavities in one attitude while two rows are orientedwith their cavities in the opposite attitude. Ideally, an equal numberof cavities should be oriented in the one attitude and the same numberoriented in the opposite attitude. However, this is inconvenient wherean odd number of rows are provided as in the disclosed embodiment. Ifsix rows of cavities were provided in this block, the most logicalarrangement would be to have three rows in one attitude and three rowsof cavities on the opposite attitude.

The particular form of block shown is provided with peripheral flangeswhich extend beyond the projecting long arms of the contacts as is morefully described in the copending application of Charles R. Curtis andLincoln E. Roberts, Serial No. 183,554, filed March 29, 1962, forMulti-contact Electrical Connector, now Patent No. 3,112,974. Theseflanges function as polarizing and keying means for the block andadditionally form a protecting shroud in surrounding relationship to theprojecting arms of the contacts.

In order that the dielectric insulating blocks 40 may be hermaphorditic,that is in order that they shall be capable of being brought intoengagement with an identical block, the cavities should be symmetricallyarranged with respect to at least one of the axes of the block. Thus, inthe disclosed embodiment of the invention, which contains 40 cavities,the cavity row identified by the letter C is symmetrically arranged withrespect to an axis extending transversely of the long dimension of theblock and centrally through the openings for the jack screws. Theflanges which surround the block must also be preferentially arranged asis fully described in the above-mentioned Curtis et al. application.

A principal advantage of the instant invention is that close spacing ofthe contacts in the dielectric blocks is achieved in spite of the factthat the contacts themselves are a hermaphroditic and nonsymmetrical (ascompared with pin and socket contacts) type of contact. The features ofthe invention which permit such close spacing without sacrifice ofelectrical or mechanical integrity in the connector are brieflydescribed below.

It will be noted that the arms 18, 20 are disposed within the planesdefined by the sidewalls 6 and 8 excepting the hooked end 36 of theshorter arm 20. The cavities are necked down at 67 so that the openingsin the mating faces of the blocks are relatively small as compared tothe openings in the rearward face 48. The divergent end 36 of the shortarm 20 of each contact is received within the recess 70 of each cavityand does not extend to the mating face of the block. The arrangement ofthe cavities in the block is such that the recesses '70 of the lowerblock in FIGURE 3 are adjacent to the recesses of the next adjacentcavity of the upper block, however, since the arms are recessed withrespect to the mating faces of the block, a relatively long path isprovided between adjacent contacts which must be electrically separatefrom each other so that a high breakdown voltage between adjacentcontacts is achieved. It should be added that while the openings in therearward ends of the cavities are relatively large, this fact does notadversely aflect the breakdown voltage of the connector between adjacentcontacts since the contacts are themselves all contained within theirrespective cavities and a relatively long path is provided betweenadjacent contacts.

Contacts of the instant type are often plated with gold or other highlyconductive metal to improve their electrical performance. into and outof engagement with each other, the plating is worn by the slidingcontact surfaces as they move over each other and may be removed after arelatively low num. ber of coupling and decoupling cycles. This wearproblem is particularly important where the contacts are gold platedsince gold plating must be kept to a minimum thickness for economicreasons. The instant type of contact reduces the plating wear to anextremely low mini mum by virtue of the contact ramp 34 and the contactdimple 36 if these parts are matched to each other as regardsinclination of the ramp and radius of the dimple. Particularly, theradius of the dimple and the inclination of the ramp should be suchthatas the dimple of one of the long arms moves over the ramp the zone oftangency of both parts, the contact zone continually changes in the samemanner as the contact zone of a ball or sphere rolling over a surfacecontinually changes as the ball moves along the surface. Since the zonesof contact of the parts continually change during movement of thecontacts into engagement with each other, the amount of wear on anygiven point is reduced to an absolute minimum.

The disclosed arrangement provides an extremely durable contact whichwill not be damaged easily in the ordinary cour-se of usage. The longcontact arms 18 of the contact terminals can be flexed towards the shortcontact arms without impairing the electrical function of the con tactsince this arm will snap back into its normal position after suchflexure. In case of slight misalignment of a given contact with respectto its mating counterpart, the parts are brought into proper alignmentas the insulating blocks are moved against each other by virtue of theinclined ramp surface of the one contact and the curved Ordinarily, whencontacts are moved contact surface of the long arm of the matingcontact. Furthermore, the actual contact force acting between eachindividual contact ramp and contact surface 28 is main tained withinrelatively close limits by reason of the rela tively long stem of thelong contact arm about its bending axis which is at the inwardlydirected cusp portion of the arm.

Contacts in accordance withthe invention are amenable to straightforwardand simplified die-forming processes as is apparent from the progressionof FIGURE 1. After stamping of the form of the contact from the strip,it is merely necessary to form the inwardly displaced intermediatesections of the contact arms 18, 20 and thereafter to bend up the sidesof the contact with respect to the web. Operations of this type can beformed with relative ease by conventional die-stamping and formingmethods.

FIGURE 8 shows a contact terminal 21 having a modified hooked endportion 36'. In accordance with this embodiment, the hooked end 36'extends obliquely of the ramp portion 34 but diverges from the plane ofthe ramp at a smaller angle than the angle of the embodiment ofFIGURE 1. A laterally extending car 37 is provided on the upper side ofthe hooked end 36 to provide a rearwardly facing edge 39. The contactterminal of FIGURE 8 is useable with a block having cavities of the typepreviously described and shown in FIGURES 36. The hooked end portion 36of the arm 20 is dimem sioned such that the ear 37 occupies asubstantial portion of the recess and the tip of the end portion 36normally bears against the left-hand Wall of this recess as viewed inFIGURE 9. A comparative advantage of this embodiment is that the surfaceof the hooked end 36' provides a somewhat wider lead-in for the long arm18 of the ma ing terminal than the lead-in of the previous embodiment.

In other words, when two contact terminals in accordance with theembodiment of FIGURE 8 are mated with each other, the long arms of theterminals will be guided into engagement with the ramp portions even ifthese long arms are initially somewhat out of alignment. It will beapparent that with the exception of this provision of a relatively widerlead-in surface, the terminal of FIG- URE 8 is similar to the terminalof FIGURE 1.

Changes in construction will occur to those skilled in the art andvarious apparently diflerent modifications and embodiments may be madewithout departing from the scope of the invention. The matter set forthin the foregoing description and accompanying drawings is offered by wayof illustration only. The actual scope of the invention is intended tobe defined in the following claims when viewed in their properperspective against the prior art.

I claim:

1. A contact terminal for an electrical connector comprising, anelongated web, a first pair of parallel sidewalls extending fromopposite sides of said Web at one end thereof and a second pair ofparallel sidewalls extending from opposite sides of said web at theopposite end thereof, means on said "web intermediate the ends thereofand between said sidewalls for securing said contact to an electricalconductor extending between said second pair of sidewalls, an armextending from and constituting a planar extension of each of said firstpair of sidewalls, a first one of said arms having an intermediate cuspportion directed inwardly towards the axis of said contact and having adiverging end portion terminating in an outwardly facing contactsurface, the second one of said arms being substantially shorter thansaid first arm and having an inwardly directed intermediate section, acontact ramp extending divergently of the axis of said contact from saidintermediate section and terminating in an outwardly hooked end portion,said contact terminal being mateable with an identical contact terminalupon axial movement of said contacts towards each other until thecontact surface of the first arm of each contact terminal engages thecontact ramp of the second arm of the other contact terminal.

2. Electrical connecting means comprising an insulating block having acontact terminal receiving cavity extending therethrough and a contactterminal in said cavity, said cavity having a rearward end, a firstsection of said cavity having a rectangular cross section extending fromsaid rearward end to a location adjacent the forward end of said cavity,one pair of opposed walls of said cavity tapering towards each other ina zone adjacent to said forward end, one of said opposed walls extendingaxially from said adjacent zone to said forward end and the other ofsaid opposed walls having a reentrant surface defining a forwardlyfacing shoulder recessed from said forward end, said contact terminalhaving a web portion disposed in said rectangular first section,upstanding parallel sidewalls on said web, said web and sidewallsbearing against the opposed walls of said first section whereby saidcontact is firmly wedged in said cavity, a first arm extending from oneof said sidewalls as a planar extension thereof, said first arm havingan intermediate cusp portion directed inwardly towards the axis of saidcontact terminal and said first arm projecting substantially beyond saidforward end, a second arm extending from a second one of said sidewalls,said second arm having an inwardly directed intermediate section and adiverging contact ramp, said second arm terminating in an outwardlyhooked end portion extending into said recess and over said forwardlyfacing shoulder, said connecting means being mateable with an identicalconnecting means disposed in axial alignment and opposed relationshipthereto upon movement of said connecting means together until the end ofthe first arm of each contact terminal engages the contact ramp of theother contact terminal.

3. Apparatus as set forth in claim 2 wherein said block has a pluralityof cavities extending therethrough, a first group of said cavitieshaving said reentrant surface on one sidewall and a second group of saidcavities having said reentrant surface on an opposite sidewall from saidfirst group whereby, when said block is brought into engagement with amating block, the lateral force produced by the contact terminals insaid first group of cavities is counteracted by the lateral forcecomponent of the contact terminals in said second group of cavities.

4. Apparatus as set forth in claim 3 wherein said first group ofcavities is arranged in a first row in said block and said second groupis arranged in'a second row.

- 5. An insertable contact terminal for an electrical connectorcomprising, an elongated web, a pair of sidewalls extending fromopposite sides of said web at one end thereof, stablizing meansextending from said web at the opposite end thereof, said stabilizingmeans and said sidewalls being cooperable with the sidewalls of aconnector block cavity to stabilize said contact terminal within saidcavity, means on said web intermediate the ends thereof for securingsaid contact to an electrical conductor, a pair of arms extending fromand constituting planar extensions of each of' said sidewalls, a firstone of said arms having an intermediate cusp portion directed inwardlytowards the axis of said contact and having a diverging end portionterminating in an outwardly facing contact surface, the second one ofsaid arms being substantially shorter than said first arm and having aninwardly directed intermediate section, a contact ramp extendingdivergently of the axis of said contact from said intermediate sectionand terminating in an outwardly hooked end portion, said contactterminal being mateable with an identical contact terminal upon axialmovement of said contacts towards each other until the contact surfaceof the first arm of each contact terminal engages the contact ramp ofthe second arm of the other contact terminal.

References Cited by the Examiner UNITED STATES PATENTS 2,326,327 8/43Brewer 339-49 3,034,089 5/62 Curtis 339-49 3,083,345 3/63 Scheller339-49 FOREIGN PATENTS 1,121,148 2/55 France.

JOSEPH-D. SEERS, Primary Examiner.

5. AN INSERTABLE CONTACT TERMINAL FOR AN ELECTRICAL CONNECTORCOMPRISING, AN ELONGATED WEB, A PAIR OF SIDEWALLS EXTENDING FROMOPPOSITE SIDES OF SAID WEB AT ONE END THEREOF, STABILIZING MEANSEXTENDING FROM SAID WEB AT THE OPPOSITE END THEREOF, SAID STABILIZINGMEANS AND SAID SIDEWALLS BEING COOPERABLE WITH THE SIDEWALLS OF ACONNECTOR BLOCK CAVITY OF STABILIZE AND CONTACT TERMINAL WITHIN SAIDCAVITY, MEANS ON SAID WEB INTERMEDIATE THE ENDS THEREOF FOR SECURINGSAID CONTACT TO AN ELECTRICAL CONDUCTOR, A PAIR OF ARMS EXTENDING FROMAND CONSTITUTING PLANAR EXTENSIONS OF EACH OF SAID SIDEWALLS, A FIRSTONE OF SAID ARMS HAVING AN INTERMEDIATE CUSP PORTION DIRECTED INWARDLYTOWARDS THE AXIS OF SAID CONTACT AND HAVING A DIVERGING END PORTIONTERMINATING IN AN OUTWARDLY FACING CONTACT SURFACE, THE SECOND ONE OFSAID ARMS, BEING SUBSTANTIALLY SHORTER THAN SAID FIRST ARM AND HAVING ANINWARDLY DIRECTED INTERMEDIATE SECTION, A CONTACT RAMP EXTENDINGDIVERGENTLY OF THE AXIS OF SAID CONTACT FROM SAID INTERMEDIATE SECTIONAND TERMINATING IN AN OUTWARDLY HOOKED END PORTION, SAID CONTACTTERMINAL BEING MATEABLE WITH AN IDENTICAL CONTACT TERMINAL UPON AXIALMOVEMENT OF SAID CONTACTS TOWARDS EACH OTHER UNTIL THE CONTACT SURFACEOF THE FIRST ARM OF EACH CONTACT TERMINAL ENGAGES THE CONTACT RAMP OFTHE SECOND ARM OF THE OTHER CONTACT TERMINAL.